Malfunction recognition

WARNING: This page is about a different car, the 2006 Audi A4, 2005 Audi A4, 2004 Audi A4, 2003 Audi A4, and 2002 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.

If malfunctions occur at the exhaust relevant systems or components, they are stored in DTC memory with a description of the malfunction type.

The stored malfunctions can be checked with a standard diagnostic tester Mode 3: Check DTC memory. See MODE 3: CHECK DTC MEMORY .

The Engine Control Module (ECM) differentiates between different DTCs after evaluating the information. See DIAGNOSTIC TROUBLE CODE (DTC) TABLES: .

If the ECM recognizes malfunctions that lead to a worsening of emissions values, it indicates them by lighting the Malfunction Indicator Lamp (MIL) -K83- in the instrument cluster. See MALFUNCTION INDICATOR LAMP (MIL) -K83- IN INSTRUMENT CLUSTER .

E-Gas -relevant malfunctions are also indicated by the Electronic Power Control (EPC) Warning Lamp -K132- ("EPC warning lamp") in the instrument cluster. See ELECTRONIC POWER CONTROL (EPC) WARNING LAMP -K132- IN INSTRUMENT CLUSTER .

When disconnecting harness connectors from Engine Control Module (ECM) or when disconnecting battery, all adaptation values in the control module are erased. DTC memory content will remain intact however. After re-connecting harness connectors or battery, the following work steps must be performed in the mentioned sequence:

- Check DTC memory "Mode 3: Check DTC memory". See MODE 3: CHECK DTC MEMORY .
- If necessary, erase DTC memory. See MODE 4: RESET/ERASE DIAGNOSTIC DATA .
- If DTC memory was erased, generate readiness code. See READINESS CODE, GENERATING .
- End diagnosis and switch ignition off.